My stock ported 6port with stock tune, aem intake and a catback pulls harder than that

 

Mine looked like that, when it first came out of the box.
This is a bone stock pull, the car was maybe 6 months old

 

Aaagh. Horrible, horrible result on my newly-acquired 2011 17,000 mile R3 (K&N air filter, Milltek catback), at least 10 bhp down on my 2009 R3 (30,000m, K&N, RB catback) on the same DynoDynamics dyno :
Note: power is at flywheel; based on 2009 car's run, the power at the wheels is around 160bhp

The shape above 6000 rpm is horrible.

Just edited to highlight that power is at flywheel; at wheels is about 160bhp.

Edited again to say 4th gear

 

195 hp isn't bad IMO

 

Is it just me or that torque curve has issues

 

That might just be the scaling of the chart.

The HP plot is scaled smaller than the Torque over emphasizing the curve, .. , maybe?

 

2.4K and 6.4k just seem like very abrupt spikes from what I am used to seeing.

 

I would agree with that...

HP curve looks mostly ok, see that weird flat-line right at 6500ish rpm. I wonder what's going on there? APV?

I wonder what gear this was done in?

 

Just added was in 4th gear

 

Still don't understand 4th gear pulls.

 

LoL

Well it is what it is ...

Still seems to be a bit of a stumble around 6250 when the APV opens.
The dip is expected but that flat blip is odd IMO and it correlates with the drop in the torque.
However there's typically a drop in torque there as well.

Likely over analyzing it

 

you missed the bit where he said "at the flywheel"

 

Brettus, that's my fault.
wcs made his comment which then prompted me to amend my post to emphasize that the results were at the flywheel

 

Hi guys,

I've been following this thread for a while, and have been to the dyno a few times trying to figure out why my car makes peak power just past 7k rpm and looks weak over 7500. The car drives fine, but I care about the last few HP because I compete in autocross (STX class). At this point I'm out of things to try, so I'm hoping you guys might have some ideas.

Here's the most recent dyno plot (in 5th gear).




Car is an '06 US-market 6MT shinka with 52k miles. The drivetrain is completely stock except for a K&N panel filter, BHR ignition kit, and a Racing Beat Rev8 exhaust.

Here's what I know
* I dyno'd the car before and after installing the BHR kit & fresh plugs. Before: power trailed off dramatically past 8000. After: curve looked like the above chart.
* I removed the stock catalytic converter & visually inspected (pic). No clogging that I could see, waffle pattern appeared undamaged.
* Measure vacuum at idle from LIM nipple at 17 inHG of vacuum (8.3 PSI)
* Compression test came back at rotor1: 6.9, 6.7, 6.9 @ 274, rotor2: 7.0, 6.9, 7.0 @ 271
* Using a vacuum pump, SSV and VDI appear to actuate correctly - fully open at 7 inHG of vacuum (3.4 PSI) and held vacuum for at least 30s (at which point I got bored)
* I can hear the APV cycling after shutting off the car.
* No CELs or error codes.
* I've done 3 dyno sessions spanning a year, and the "normal" part of the graph (< 7k rpm) has gotten slightly worse each time - not sure if this is related, a separate problem, or just noise.
* Ambient temperature is always around 80F, and elevation is a few feet above sea level.
* At some point in time after the first dyno, I cleaned the MAF.

Compression is low, but I thought that mainly affected low-end power?

Prior to the last dyno session, I took it to a local rotary mechanic for the compression test followed by a decarb. He mentioned that there was a lot of crud on the plugs and recommended that I go one step colder for the leading plug. He installed the new plugs, so I'm not sure of the part numbers, but he said the leading plugs were now the same as the trailing. I'd noticed brown crud on the plugs in previous plug swaps (pic), but assumed it was normal?

During the last dyno session, I also logged data from OBD, available here.

In those logs, I see MAF readings of 4.7 g/s at idle and peaking around 208 @ 8700 rpm, which I think is normal? I don't know what to make of the fuel trim and timing advance numbers.

Thoughts?

 

Compression is low, that's why you're missing around 30hp here and there.
Rebuild the engine, break it in, tune it and dyno it again.

 

Low compression

Your HP is so low because your torque is low.

 

That's what I was afraid of. Compression isn't low enough to get a free reman engine from Mazda under warranty either

 

Your engine is below spec, you should be able to get a reman.
a 208g\s maf reading is fairly low too. My NA engine pulled around 270g\s at around the same rpm.
I'm not twisting the knife in your cut, just be happy to get the chance to either get a reman engine or build one the right way. The performance "increase" will be very noticeable and you'll enjoy many successful autoX runs

 

208 is not to bad 270 is a wet dream ...................

 

Why would I lie brettspeed?
I don't even have an rx8 anymore, it's not like i'd be interested in a pissing contest.

 

are you serious ? To get 270g/s would take major modifications ... like a turbo for instance .
Even ported engines with every conceivable bolt on struggle to get 240. A healthy stock engine generally is around 210-220 .

 

270g\s translates to roughly 210rwhp. It's not 100% accurate but that's the ballpark.
A well tuned engine on a modified car doesn't struggle to see those numbers.

 

Before my reman went I was doing 230's when it was hot and touch 240 if it was cold maybe fully tuned... Every bolt on minus headers... 270g/s would be pretty insane imo but then again it could be a bomb *** built engine, who knows?!

 

Not wanting a pissing contest either . Just trying to get some perspective for the guy who posted his results . 208 is actually not abnormal ------ I have many NA logs from different 8s that back that up.

 

Perhaps there's a difference in the readings of a scaled MAF vs those of a non-scaled one?